Method for parallel ink-jet printing of perovskite thin film through multi-ink-path system and application

Abstract

The invention discloses a method for parallel ink-jet printing of a perovskite thin film through a multi-ink-path system and application, and the method comprises the steps: preparing an organic ammonium salt solution and three passivation solutions, including a first passivation solution, a second passivation solution and a third passivation solution; evaporating lead iodide on the substrate to form an inorganic skeleton layer; the organic ammonium salt solution, the first passivation solution, the second passivation solution and the third passivation solution are sequentially ink-jet printed on the inorganic framework layer in parallel through a multi-ink-path system for deposition; and carrying out gradient annealing treatment on the deposition liquid to form the perovskite thin film. According to the invention, the organic ammonium salt solution and various passivation solutions are prepared and are sequentially ink-jet printed on the inorganic skeleton layer in parallel by adopting the multi-ink-path system, and the preparation of the large-area and high-quality perovskite thin film is realized in combination with gradient annealing treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of organic electro-solid state devices, and particularly to organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelengths or particulate radiation. Specifically, it is a method and application for parallel inkjet printing of perovskite thin films using a multi-ink path system. Background Art

[0002] As the third-generation solar cell technology, perovskite solar cells have high conversion efficiency, low cost and environmental protection characteristics, and have become a research hotspot in the field of solar cells. Compared with the first-generation crystalline silicon solar cells and the second-generation thin-film solar cells of multiple compounds, perovskite solar cells have multiple advantages such as rich raw material reserves, low cost, simple process and flexible preparation. Their theoretical conversion efficiency is as high as 33%, and they can be combined with crystalline silicon solar cells to form tandem solar cells to further improve the conversion efficiency.

[0003] In the preparation process of perovskite solar cells, the preparation of perovskite thin films is a key step: Although the traditional spin coating method can obtain high-quality thin films, there are some limitations. The spin coating method will cause uneven film thickness in large-area preparation. The solution at the edge of the substrate dries faster than the central area, forming a thickness gradient, which affects the quality and performance of large-area perovskite thin films. The deposition speed of the spin coating method is relatively slow, and the area of each spin coating is limited, making it difficult to meet the requirements of large-area and high-speed industrial production. The low efficiency of the spin coating method will become a bottleneck, restricting the production efficiency and cost control of perovskite solar cells.

[0004] In the preparation process of perovskite solar cells, due to the low preparation temperature of perovskite thin films and the difficult control of the nucleation and growth process, a large number of defects will be generated during the crystallization process of perovskite, such as metal lead, iodine vacancies and formamidine vacancies. In addition, in the two-step method, organic ammonium salts will remain on the surface of perovskite thin films, making perovskite have a strong p-type surface, which is not conducive to electron transfer. These problems seriously limit the further improvement of the performance of perovskite solar cells.

[0005] Therefore, it is necessary to improve the method for preparing perovskite thin films in the prior art to solve the above problems. Summary of the Invention

[0006] The present invention overcomes the deficiencies of the prior art and provides a method and application for parallel inkjet printing of perovskite thin films using a multi-ink path system, aiming to improve the film-forming quality of large-area perovskite, improve the performance of perovskite solar cells, and meet the requirements of large-scale and high-speed production at the same time.

[0007] To achieve the above object, the technical solution adopted by the present invention is: A method for parallel inkjet printing of perovskite thin films using a multi-ink path system, comprising the steps:

[0008] S1. Prepare an organic ammonium salt solution and three passivation solutions, including: a first passivation solution, a second passivation solution, and a third passivation solution;

[0009] S2. Evaporate lead iodide on the substrate to form an inorganic framework layer;

[0010] S3. Print the organic ammonium salt solution, the first passivation solution, the second passivation solution, and the third passivation solution onto the inorganic framework layer in parallel and sequential order through a multi-ink path system for deposition;

[0011] S4. Perform gradient annealing treatment on the deposited liquid to form a perovskite thin film.

[0012] In a preferred embodiment of the present invention, it is characterized in that: the organic ammonium salt solution is prepared from formamidinium hydroiodide and methylammonium chloride, and the concentration of the organic ammonium salt solution is 0.5 - 1.5 M.

[0013] In a preferred embodiment of the present invention, it is characterized in that: the first passivation solution is an isopropanol solution of cesium iodide, cesium bromide, or cesium chloride, and the concentration of the first passivation solution is 0.05 - 1 mg / ml; the second passivation solution is an isopropanol solution of lead acetate or lead nitrate, and the concentration of the second passivation solution is 0.01 - 0.1 mg / ml; the third passivation solution is an isopropanol solution of octylammonium iodide or phenethylammonium iodide derivative, and the concentration of the third passivation solution is 1 - 5 mg / ml.

[0014] In a preferred embodiment of the present invention, it is characterized in that: the substrate is composed of a substrate and a transparent conductive oxide layer attached to the substrate; the substrate is one or a mixture of one or more of flexible and rigid substrates such as glass, silicon wafer, polyethylene naphthalate, polyethylene terephthalate, polyimide, polybutylene terephthalate, polydimethylsiloxane and its derivatives; the transparent conductive oxide layer is one or a mixture of one or more of indium tin oxide, aluminum-doped zinc oxide, indium-doped zinc oxide, fluorine-doped tin oxide, indium tungsten oxide, and indium cerium oxide.

[0015] In a preferred embodiment of the present invention, it is characterized in that: in step S3, a multi-channel inkjet printing system is used, and the multi-ink path system includes at least four independent inkjet printing heads, and each inkjet printing head corresponds to a solution; wherein, the first inkjet printing head prints the organic ammonium salt solution, the second inkjet printing head prints the first passivation solution, the third inkjet printing head prints the second passivation solution, and the fourth inkjet printing head prints the third passivation solution.

[0016] In a preferred embodiment of the present invention, it is characterized in that: in step S3, the inkjet printing sequence includes:

[0017] S31. The first inkjet printing head prints the organic ammonium salt solution onto the inorganic framework layer, and the inkjet printing interval time between the organic ammonium salt solution and the first passivation solution is 5 - 15 seconds;

[0018] S32. The second inkjet printing head prints the first passivation solution, and the inkjet printing interval time between the first passivation solution and the second passivation solution is 1 to 10 seconds;

[0019] S33. The third inkjet printing head prints the second passivation solution, and the inkjet printing interval time between the second passivation solution and the third passivation solution is 1 to 10 seconds;

[0020] S34. The fourth inkjet printing head prints the third passivation solution;

[0021] The printing resolution range of the first inkjet printing head is 100 dpi to 2400 dpi, the droplet volume range of the printing nozzle is 1 to 50 pL, and the ejection frequency is 10 to 500 kHz; the printing resolution ranges of the second inkjet printing head, the third inkjet printing head and the fourth inkjet printing head are 100 dpi to 2400 dpi, the droplet volume range of the printing nozzle is 1 to 50 pL, and the ejection frequency is 10 to 500 kHz.

[0022] In a preferred embodiment of the present invention, it is characterized in that: the gradient annealing is divided into three stages:

[0023] The temperature in the preheating stage is 50 to 100 °C, the heating rate is 2 to 5 °C / s, and the duration is 2 to 5 minutes;

[0024] The main annealing stage is 100 to 170 °C, the heating rate is 1 to 2 °C / s, and the duration is 10 to 30 minutes;

[0025] In the slow cooling stage, the temperature is cooled to 50 °C, the cooling rate is 0.5 to 1 °C / s, and the duration is 5 to 10 minutes.

[0026] The present invention provides a perovskite thin film, which is prepared by a method of parallel inkjet printing a perovskite thin film through a multi-ink path system.

[0027] The present invention provides a perovskite solar cell, and the perovskite solar cell includes: a transparent conductive glass, a hole transport layer, the perovskite thin film, an electron transport layer and a metal electrode which are arranged in sequence.

[0028] The present invention provides a preparation method of a perovskite tandem solar cell, and a hole transport layer, the perovskite thin film, an electron transport layer and a metal electrode are sequentially formed on the transparent conductive glass.

[0029] The present invention solves the defects existing in the background technology, and the present invention has the following beneficial effects:

[0030] (1) The present invention provides a method for parallel inkjet printing of perovskite films using a multi-ink channel system. By configuring an organic ammonium salt solution and multiple passivation solutions, and using the multi-ink channel system to perform parallel sequential printing onto an inorganic framework layer, combined with gradient annealing treatment, the preparation of large-area and high-quality perovskite films is achieved, significantly improving the performance of perovskite solar cells and solving the problems of uneven film thickness and many defects in large-area preparation by traditional methods.

[0031] (2) After the present invention realizes the sequential deposition of the organic ammonium salt and three passivation agents through the multi-ink channel system, combined with the temperature control of gradient annealing, an integrated process of "deposition - penetration - crystallization - repair" is formed. Specifically, in the preheating stage, cesium salt is promoted to diffuse into the perovskite bulk phase to fill iodine vacancies. In the main annealing stage, lead salt compensates for lead vacancies and induces grain coalescence. In the slow cooling stage, a stable 2D / 3D heterojunction is constructed through the π-π interaction of the organic ammonium salt. The parallel printing of the multi-ink channel system ensures the efficient deposition and uniform distribution of multiple solutions. The gradient annealing treatment realizes the directional growth and defect repair of perovskite crystals through precise temperature control; significantly improves the crystallinity and stability of the perovskite film, reduces the defect density, and enhances the optoelectronic properties of the film. The traditional spin-coating method requires multiple spin-coatings and annealings, with a complex process and high time cost. The method of the present invention can achieve the deposition of multiple passivation materials through one printing and one annealing, simplifies the process flow, and improves production efficiency.

[0032] (3) The present invention forms a three-level passivation mechanism of "bulk phase - interface - surface" by inkjet printing the first passivation solution, the second passivation solution, and the third passivation solution in sequence at intervals of 5 - 15 seconds. Cs + rapidly penetrates into the PbI2 lattice during the initial deposition stage, and its ionic radius precisely matches the FA + vacancy; subsequently, Pb 2 + preferentially deposits at the grain boundaries to compensate for lead deficiency; finally, phenethylammonium iodide forms a dense passivation layer on the surface. The three work together to reduce the density of defect states, increase the open-circuit voltage, break through the bottleneck of traditional single passivation agents, improve the crystallinity and uniformity of the perovskite film, reduce surface defects, and enhance the optoelectronic properties of the film.

[0033] (4) The gradient annealing of the present invention is divided into a preheating stage, a main annealing stage, and a slow cooling stage. The preheating stage is used to slowly remove residual solvents to avoid film cracking caused by rapid volatilization; the main annealing stage is used to promote the complete crystallization of perovskite crystals and repair lattice defects; the slow cooling stage is used to release the internal stress in the film to avoid lattice distortion caused by rapid cooling. This combination of gradient annealing treatment ensures the uniformity and stability of the perovskite film during annealing, further improving the quality and performance of the film. Compared with the single annealing temperature in the prior art, this gradient annealing treatment can better control the growth and defect repair process of perovskite crystals. Description of the Drawings

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings;

[0035] Figure 1 is a schematic diagram of parallel printing of perovskite thin films by a multi-ink path system according to a preferred embodiment of the present invention;

[0036] Figure 2 is a schematic diagram of the structure of a perovskite battery according to a preferred embodiment of the present invention;

[0037] Figure 3 is a comparison chart of JV curves according to a preferred embodiment of the present invention. Detailed Embodiments

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0039] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited by the specific embodiments disclosed below.

[0040] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as limiting the scope of protection of the present application. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Therefore, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0041] Application Overview:

[0042] In the prior art, the modification of perovskite thin films with ammonium salts, as an effective means to improve the performance of perovskite solar cells, has been widely used in the field of perovskite solar cells. However, in the special case of large-area preparation of perovskite thin films, traditional methods face many challenges.

[0043] Traditional spin coating methods have many defects when preparing large-area perovskite thin films. Since the solution at the edge of the substrate dries faster than the central region during the spin coating process, the film thickness gradually decreases from the center to the edge, forming a thickness gradient, which seriously affects the uniformity and quality of the film; the deposition rate of the spin coating method is relatively slow, and the area of each spin coating is limited, making it difficult to meet the requirements of large-area and high-speed industrial production; in order to passivate the perovskite thin film, it is often necessary to spin coat different solutions multiple times, which not only increases the complexity and time cost of the process, but also may lead to unstable film quality; the spin coating method is prone to edge effects on large-area substrates, further affecting the overall performance of the film; the spin coating method requires high-precision rotating equipment and strict process control, with high equipment costs, and it is difficult to achieve uniform rotation speed and solution distribution on large-area substrates.

[0044] In view of the above defects, the present invention proposes a method for parallel inkjet printing of perovskite thin films using a multi-ink path system. This method can effectively improve the crystallinity of the thin film and reduce surface defects by parallel printing of organic ammonium salt solutions and multiple passivating agent solutions through a multi-ink path system, and can also accelerate the deposition time of perovskite thin films, realizing the high-quality preparation of large-area perovskite thin films.

[0045] Exemplary method:

[0046] As Figure 1 shown, a method for parallel inkjet printing of perovskite thin films using a multi-ink path system includes the steps of:

[0047] S1. Prepare an organic ammonium salt solution and three passivating solutions, including: a first passivating solution, a second passivating solution, and a third passivating solution;

[0048] S2. Evaporate lead iodide on the substrate to form an inorganic framework layer;

[0049] S3. Sequentially print the organic ammonium salt solution, the first passivating solution, the second passivating solution, and the third passivating solution onto the inorganic framework layer through a multi-ink path system for deposition;

[0050] S4. Perform gradient annealing treatment on the deposited liquid to form a perovskite thin film.

[0051] At present, modifying perovskite thin films with ammonium salts is one of the effective means to improve the performance of perovskite solar cells. However, a single ammonium salt cannot passivate multiple defects simultaneously. Therefore, in this application, the use of multiple passivation materials in synergy can obtain perovskite thin films with higher performance.

[0052] In step S1, the organic ammonium salt solution is prepared from formamidinium hydroiodide and methylammonium chloride, and the concentration of the organic ammonium salt solution is 0.5 - 1.5 M. Specifically, 180 mg of formamidinium hydroiodide and 20 mg of methylammonium chloride are dissolved in 2 mL of isopropanol, and stirred thoroughly for 12 h to ensure complete dissolution, forming a 1 M organic ammonium salt solution.

[0053] Components such as formamidinium hydroiodide and methylammonium chloride in the organic ammonium salt solution can react with lead ions in the inorganic framework to form a perovskite structure.

[0054] The first passivation solution is an isopropanol solution of cesium iodide, cesium bromide or cesium chloride, and the concentration of the first passivation solution is 0.05 - 1 mg / ml. Specifically, 0.5 mg of cesium iodide is dissolved in 1 mL of isopropanol to form the first passivation solution.

[0055] Cesium ions have a relatively small ionic radius, can fill the formamidinium vacancies in the perovskite lattice, and can stabilize the lattice structure; cesium ions form strong ionic bonds with lead ions in the perovskite lattice, enhancing the stability of the lattice; in addition, cesium ions can also effectively passivate iodine vacancies in the perovskite thin film, reducing non-radiative recombination centers.

[0056] The second passivation solution is an isopropanol solution of lead acetate or lead nitrate, and the concentration of the second passivation solution is 0.01 - 0.1 mg / ml. Specifically, 0.1 mg of lead acetate is dissolved in 1 mL of isopropanol to form the second passivation solution.

[0057] Lead ions can compensate for lead vacancies in the perovskite thin film, reducing the defect density; lead ions play the role of a nucleation center during the perovskite crystallization process, promoting the uniform growth of crystals; in addition, lead ions form strong ionic bonds with iodine ions in the perovskite lattice, stabilizing the lattice structure.

[0058] The third passivation solution is an isopropanol solution of octylammonium iodide or phenethylammonium iodide derivatives, and the concentration of the third passivation solution is 1 - 5 mg / ml. Specifically, 3 mg of phenethylammonium iodide is dissolved in 1 mL of isopropanol to form the third passivation solution.

[0059] The organic ammonium ions in phenethylammonium iodide can form a passivation layer on the surface of the perovskite film, reducing surface defects. The organic ammonium ions form coordination bonds with lead ions in the perovskite lattice to construct a 2D / 3D heterojunction, improving the carrier transport efficiency. The benzene ring structure in the organic ammonium ions forms π-π interactions with iodide ions in the perovskite lattice, enhancing the stability of the film.

[0060] A single passivation material cannot simultaneously solve multiple defects in the perovskite film. The synergistic effect of the above-mentioned multiple passivation materials can achieve comprehensive passivation, significantly improving the film quality. Cesium ions stabilize the lattice structure and passivate iodine vacancies, lead ions compensate for lead vacancies and promote crystal growth, while organic ammonium ions form a passivation layer on the film surface and construct a 2D / 3D heterojunction. These materials work together to comprehensively passivate multiple defects in the perovskite film, significantly improving the film quality.

[0061] During the preparation process of the perovskite film, the selection of the substrate has an important impact on the quality and performance of the film. In step S2, the substrate consists of a substrate and a transparent conductive oxide layer attached to the substrate;

[0062] The substrate is the support layer of the substrate. Considering mechanical strength, thermal stability, light transmittance, and compatibility with the TCO layer, the substrate is one or a mixture of flexible and rigid substrates such as glass, silicon wafer, polyethylene naphthalate, polyethylene terephthalate, polyimide, polybutylene terephthalate, polydimethylsiloxane, and its derivatives;

[0063] The TCO layer is the key functional layer of the substrate, used to provide conductivity and light transmittance. The transparent conductive oxide layer is one or a mixture of indium tin oxide, aluminum-doped zinc oxide, indium-doped zinc oxide, fluorine-doped tin oxide, indium tungsten oxide, and indium cerium oxide.

[0064] The reasonable selection and combination of the substrate and the TCO layer provide a basis for the efficient formation and performance optimization of the perovskite film, enabling the overall substrate to meet the dual requirements of conductivity and light transmittance during the preparation process of the perovskite film.

[0065] Place the above substrate in a vacuum coating equipment, evacuate the evaporation chamber, and the vacuum degree reaches 1e - 4 Pa or less; Place lead iodide in the evaporation chamber, heat the lead iodide material to evaporate it at high temperature, and the evaporation rate is Form steam, and the steam deposits on the surface of the transparent conductive oxide layer of the substrate to form a uniform lead iodide film with a thickness of 200-500 nm as the perovskite inorganic framework; After the evaporation is completed, take out the substrate from the evaporation equipment, clean and process it to ensure the surface is clean. The inorganic framework layer provides the necessary structural support and reaction substrate for the subsequent formation of the perovskite film.

[0066] Parallel printing of the multi-ink path system enables the parallel injection and deposition of multiple solutions by multiple inkjet print heads and independent ink paths working simultaneously. It can precisely control the injection parameters of each inkjet print head, including injection time, injection volume, and injection position, thus achieving efficient deposition of complex materials.

[0067] Traditional spin coating methods have problems such as uneven film thickness and edge effects when preparing perovskite films on a large scale. Parallel printing of the multi-ink path system can achieve large-area and uniform film deposition, and can use multiple passivation materials simultaneously to achieve comprehensive passivation of the perovskite film.

[0068] In step S3, a multi-channel inkjet printing system is adopted. The multi-ink path system includes more than four independent inkjet print heads, and each inkjet print head corresponds to a solution; among them, the first inkjet print head prints an organic ammonium salt solution, the second inkjet print head prints the first passivation solution, the third inkjet print head prints the second passivation solution, and the fourth inkjet print head prints the third passivation solution;

[0069] S31. The first inkjet print head prints the organic ammonium salt solution onto the inorganic framework layer as the main film-forming component of the perovskite precursor; the printing resolution range of the first inkjet print head is 100 dpi to 2400 dpi, the droplet volume range of the printing nozzle is 1 to 50 pL, and the injection frequency is 10 to 500 kHz; the inkjet printing interval time between the organic ammonium salt solution and the first passivation solution is 5 to 15 seconds;

[0070] S32. After the printing of the organic ammonium salt solution is completed, the second inkjet print head prints the first passivation solution to fill the lattice vacancies and stabilize the perovskite structure; the printing resolution range of the second inkjet print head is 100 dpi to 2400 dpi, the droplet volume range of the printing nozzle is 1 to 50 pL, and the injection frequency is 10 to 500 kHz; the inkjet printing interval time between the first passivation solution and the second passivation solution is 1 to 10 seconds;

[0071] S33. After the printing of the first passivation solution is completed, the third inkjet print head prints the second passivation solution to compensate for lead vacancies and promote crystal growth; the printing resolution range of the third inkjet print head is 100 dpi to 2400 dpi, the droplet volume range of the printing nozzle is 1 to 50 pL, and the injection frequency is 10 to 500 kHz; the inkjet printing interval time between the second passivation solution and the third passivation solution is 1 to 10 seconds;

[0072] S34. After the printing of the second passivation solution is completed, the fourth inkjet printhead prints the third passivation solution for surface passivation and the construction of a 2D / 3D heterojunction; the printing resolution range of the fourth inkjet printhead is 100 dpi to 2400 dpi, the droplet volume range of the printing nozzles is 1 to 50 pL, and the ejection frequency is 10 to 500 kHz.

[0073] The above steps work together with multiple inkjet printheads to achieve an integrated process of synchronous deposition - passivation - modification. The inkjet printhead array adopts a staggered arrangement pattern, the substrate temperature is controlled at 45 ± 2 °C, and the solvent evaporation rate matches the deposition rate.

[0074] In step S4, the gradient annealing is divided into three stages, and the directional growth and defect repair of perovskite crystals are achieved through precise temperature control;

[0075] In the preheating stage, the temperature is 50 to 100 °C, and the heating rate is 2 to 5 °C / s, which is used to slowly remove the residual solvent to avoid film cracking caused by rapid evaporation. The duration is 2 to 5 minutes;

[0076] In the main annealing stage, it is 100 to 170 °C, and the heating rate is 1 to 2 °C / s, which is used to promote the complete crystallization of perovskite crystals and repair lattice defects. The duration is 10 to 30 minutes;

[0077] In the slow cooling stage, the temperature is cooled down to 50 °C, and the cooling rate is 0.5 to 1 °C / s, which is used to release the internal stress in the film to avoid lattice distortion caused by rapid cooling. The duration is 5 to 10 minutes, forming a perovskite film.

[0078] The above gradient annealing makes the perovskite grain size uniform and reduces the grain boundaries.

[0079] The preheating stage promotes the initial reaction between the organic ammonium salt and the PbI2 framework to form perovskite crystal nuclei, and the cesium salt diffuses to the lattice vacancies to inhibit the generation of iodine vacancies;

[0080] In the main annealing stage, the lead salt compensates for the lead vacancies, and at the same time promotes the grain merging. The grain size changes from 200 nm to 500 nm, and the organic ammonium salt forms a 2D perovskite layer on the surface, reducing the surface defect density;

[0081] In the slow cooling stage, the π - π interaction between the organic ammonium ions and the perovskite lattice is enhanced, improving the film stability. The stress release reduces the grain boundary cracks and improves the carrier mobility.

[0082] The combination of the gradient annealing process and the multiple passivation solutions printed by the multi - ink path system realizes the precise defect repair, crystal directional growth, and interface energy level optimization of the perovskite film through the three - dimensional coordinated regulation of temperature - time - component.

[0083] Example 1:

[0084] Dissolve 180 mg of formamidine hydroiodide and 20 mg of methylammonium chloride in 2 mL of isopropanol, and stir well for 12 h before use to obtain a 1 M organic ammonium salt solution;

[0085] Dissolve 0.5 mg of cesium iodide in 1 mL of isopropanol to form a first passivation solution; dissolve 0.1 mg of lead acetate in 1 mL of isopropanol to form a second passivation solution; dissolve 3 mg of phenethylammonium iodide in 1 mL of isopropanol to form a third passivation solution;

[0086] Place the glass substrate deposited with indium tin oxide in a vacuum coating equipment and use the evaporation rate to evaporate PbI2, and evaporate an inorganic lead salt film with a thickness of 450 nm as the perovskite inorganic framework;

[0087] Print the organic ammonium salt solution onto the inorganic framework layer using a first inkjet print head, and set the printing parameters as follows: the printing resolution ranges from 1700 dpi, the droplet volume of the printing nozzle ranges from 25 pL, and the ejection frequency is 3000 Hz;

[0088] 10 s after the printing of the organic ammonium salt solution is completed, print the first passivation solution using a second inkjet print head, and set the printing parameters as follows: the printing resolution ranges from 900 dpi, the droplet volume of the printing nozzle ranges from 20 pL, and the ejection frequency is 5000 Hz. After an interval of 5 s, print the second passivation solution using a third inkjet print head with the same printing parameters. Then, use the same method to print the third passivation solution using a fourth inkjet print head;

[0089] Perform gradient annealing. The temperature in the preheating stage is 75 °C, the heating rate is 3 °C / s, and the duration is 3 minutes; the main annealing stage is at 150 °C, the heating rate is 2 °C / s, and the duration is 25 minutes; the slow cooling stage is from 150 °C to 50 °C, the cooling rate is 1 °C / s, and the duration is 8 minutes to form a perovskite film.

[0090] Example 2:

[0091] A method for parallel inkjet printing of perovskite films using a multi-ink path system. The same parts as in Example 1 will not be described in detail. The difference between this example and Example 1 is that;

[0092] The printing time between the passivation solutions is 3 s.

[0093] Example 3:

[0094] A method for parallel inkjet printing of perovskite films using a multi-ink path system. The same parts as in Example 1 will not be described in detail. The difference between this example and Example 1 is that;

[0095] The printing time between the passivation solutions is 7 s.

[0096] Example 4:

[0097] A method for parallel inkjet printing of perovskite films using a multi-ink channel system, the same parts as in Example 1 will not be described in detail. The differences between this example and Example 1 are as follows;

[0098] The printing time between the passivation solutions is 10 s.

[0099] Example 5

[0100] A method for parallel inkjet printing of perovskite films using a multi-ink channel system, the same parts as in Example 1 will not be described in detail. The differences between this example and Example 1 are as follows;

[0101] The temperature in the main annealing stage is 130 °C.

[0102] Example 6

[0103] A method for parallel inkjet printing of perovskite films using a multi-ink channel system, the same parts as in Example 1 will not be described in detail. The differences between this example and Example 1 are as follows;

[0104] The temperature in the main annealing stage is 170 °C.

[0105] Experimental Example 1:

[0106] In this experimental example, the perovskite films prepared in Examples 1 to 4 were selected to detect the parameters of the surface coverage rate, crystallinity, and fill factor of the perovskite films. By comparing the effects of different printing intervals of the passivation solutions on the performance of the perovskite films, the effectiveness of optimizing the printing interval in improving the quality of the perovskite films can be further verified.

[0107] Table 1 Effects of printing interval on the performance of perovskite films

[0108] Example Printing interval / s Surface coverage rate / % Crystallinity / XRD intensity Fill factor / % Example 1 5 99.8 96 82 Example 2 3 97.5 88 77 Example 3 7 98.2 94 80 Example 4 10 95.0 80 73

[0109] When the printing interval of the passivation solution is 5 s, the surface coverage rate, crystallinity, and fill factor of the perovskite film all reach the best values.

[0110] Too short an interval time causes the organic ammonium salt solution not to fully penetrate into the PbI2 framework and is then covered by the subsequent passivating agent solution, resulting in a decrease in crystallinity and an increase in surface defects; too long an interval time causes excessive solvent evaporation, hindering the diffusion of the passivating agent, insufficient compensation for lead vacancies, and an uneven surface passivation layer. Through the timing control of the multi-ink channel system, it is ensured that each passivation solution penetrates into the bulk phase → subsurface → surface of the perovskite film in sequence, realizing the layer-by-layer repair of defects and avoiding the passivation failure caused by solution mixing in the traditional spin-coating method.

[0111] Experimental Example 2:

[0112] In this test example, the perovskite thin films prepared in Example 1, Example 5 and Example 6 were selected to detect the crystallinity, lead vacancy density and stability of the perovskite thin films. By studying the influence of different annealing temperatures on the performance of the perovskite thin films, the effectiveness of optimizing different annealing temperatures in improving the quality of the perovskite thin films was verified.

[0113] Table 2 Influence of Different Annealing Temperatures on the Performance of Perovskite Thin Films

[0114] Example Main annealing temperature / °C Crystallinity / XRD intensity <![CDATA[Lead vacancy density / cm -3 > Stability / T80, h Example 1 150 96 <![CDATA[2×10 14 > 1200 Example 5 130 78 <![CDATA[1×10 15 > 800 Example 6 170 65 <![CDATA[5×10 15 > 400

[0115] When the main annealing temperature is 150 °C, the crystallinity, lead vacancy density and stability of the perovskite thin film are optimal. Too low a temperature will lead to incomplete crystal growth, a high lead vacancy density, and residual solvents causing grain boundary cracks. Too high a temperature will cause the decomposition of organic ammonium salts, excessive migration of lead ions leading to lattice distortion and damage to the two-dimensional passivation layer. Gradient annealing controls the temperature in three stages: preheating → main annealing → slow cooling, which not only promotes the repair of bulk defects of cesium salt / lead salt but also preserves the integrity of the surface 2D perovskite layer, making the thin film have both high crystallinity and long-term stability.

[0116] Device Example:

[0117] As Figure 2 shown, this example provides a method for preparing a perovskite tandem solar cell, including the following steps:

[0118] Select a 25 mm × 25 mm transparent conductive glass ITO as the substrate;

[0119] Deposit Me-4PACz as the hole transport layer on the ITO layer by spin coating, with a spin coating speed of 4000 rpm, a spin coating time of 30 s, an annealing temperature of 100 °C, and an annealing time of 10 min;

[0120] Prepare the perovskite thin film using Example 1;

[0121] Deposit 25 nm of C60 as the electron transport layer on the perovskite thin film by evaporation, with a deposition rate of

[0122]

[0123] Deposit 8 nm of BCP as the buffer layer on the electron transport layer by evaporation;

[0124] Prepare 200 nm of Ag as the metal electrode by thermal evaporation, with a deposition rate of

[0125] Device Comparative Example:

[0126] Select a 25 mm × 25 mm transparent conductive glass ITO as the substrate;

[0127] The Me-4PACz was deposited on the ITO layer by spin coating as the hole transport layer. The spin coating speed was 4000 rpm, the spin coating time was 30 s, the annealing temperature was 100 °C, and the annealing time was 10 min;

[0128] Using PbI2 was evaporated at an evaporation rate to deposit an inorganic lead salt film with a thickness of 450 nm as the perovskite inorganic framework. Subsequently, the organic ammonium salt solution was dynamically spin-coated at 2500 rpm for 10 s. The first passivation solution, the second passivation solution, and the third passivation solution were dynamically spin-coated at 2500 rpm in sequence, with a 10 s interval between each spin coating. Annealing was performed at 150 °C for 30 min to form the perovskite film;

[0129] Using evaporation to deposit 25 nm of C60 on the perovskite film as the electron transport layer, and the deposition rate was

[0130]

[0131] Using evaporation to deposit 8 nm of BCP on the electron transport layer as the buffer layer;

[0132] Using thermal evaporation to prepare 200 nm of Ag as the metal electrode, and the deposition rate was

[0133] Experimental Example III;

[0134] As Figure 3 shown, in this experimental example, device examples and device comparative examples were selected for testing to verify the electrical performance of the perovskite tandem solar cell;

[0135] Table 3 Comparison of electrical parameters between device examples and device comparative examples

[0136] Group <![CDATA[Jsc (mA / cm 2 )]]> Voc (V) FF (%) PCE (%) Device example 23.64 1.02 75 18.08 Device comparative example 23.88 0.97 78 18.06

[0137] Although the short-circuit current and fill factor of the traditional spin coating method are slightly higher than those of the method of this application, the open-circuit voltage of this application is significantly improved, and the efficiencies of the two are close. This is because the spin coating method leads to an increase in carrier recombination due to uneven thickness, and multiple spin coatings cause interface contamination. In this application, the uniform deposition by multi-ink path printing reduces the surface defect density of the perovskite film by 60%. Although the difference in microcrystallinity causes a slight loss of Jsc / FF, the industrial compatibility and large-area stability are significantly better than the spin coating process, solving the problem that the traditional method cannot balance uniformity, speed, and stability.

[0138] Based on the above inspiration from the ideal embodiments of the present invention, through the above description, relevant personnel can completely make various changes and modifications without departing from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. A method for parallel inkjet printing of perovskite thin films using a multi-ink system, characterized in that: Includes steps: S1, preparing an organic ammonium salt solution and three passivation solutions, including: a first passivation solution, a second passivation solution and a third passivation solution; S2, evaporating lead iodide on the substrate to form an inorganic skeleton layer; S3, printing the organic ammonium salt solution, the first passivation solution, the second passivation solution and the third passivation solution in parallel and sequentially onto the inorganic skeleton layer through a multi-ink path system for deposition; S4. Performing gradient annealing on the deposited liquid to form a perovskite film.

2. The method for parallel inkjet printing of perovskite thin films using a multi-ink path system according to claim 1, characterized in that: The organic ammonium salt solution is prepared by reacting formamidine hydroiodide and methylammonium chloride, and the concentration of the organic ammonium salt solution is 0.5-1.5M.

3. The method for parallel inkjet printing of perovskite thin films using a multi-ink path system according to claim 1, characterized in that: The first passivation solution is an isopropanol solution of cesium iodide, cesium bromide or cesium chloride, and the concentration of the first passivation solution is 0.05-1 mg / ml; the second passivation solution is an isopropanol solution of lead acetate or lead nitrate, and the concentration of the second passivation solution is 0.01-0.1 mg / ml; the third passivation solution is an isopropanol solution of octyl ammonium iodide or a phenethyl ammonium iodide derivative, and the concentration of the third passivation solution is 1-5 mg / ml.

4. The method for parallel inkjet printing of perovskite thin films using a multi-ink path system according to claim 1, characterized in that: The substrate is composed of a substrate and a transparent conductive oxide layer attached to the substrate; the substrate is one or more mixtures of flexible and rigid substrates of glass, silicon wafer, polyethylene naphthalate, polyethylene terephthalate, polyimide, polybutylene terephthalate, polydimethylsiloxane and derivatives thereof; the transparent conductive oxide layer is one or more mixtures of indium tin oxide, aluminum-doped zinc oxide, indium-doped zinc oxide, fluorine-doped tin oxide, indium tungsten oxide and indium cerium oxide.

5. The method for parallel inkjet printing of perovskite thin films using a multi-ink path system according to claim 1, characterized in that: In step S3, a multi-channel inkjet printing system is used, and the multi-ink path system includes at least four independent inkjet print heads, each inkjet print head corresponds to a solution; wherein the first inkjet print head prints an organic ammonium salt solution, the second inkjet print head prints a first passivation solution, the third inkjet print head prints a second passivation solution, and the fourth inkjet print head prints a third passivation solution.

6. The method for parallel inkjet printing of perovskite thin films using a multi-ink path system according to claim 1, characterized in that: In step S3, the inkjet printing sequence includes: S31, the first inkjet print head prints the organic ammonium salt solution onto the inorganic skeleton layer, and the interval time between the inkjet printing of the organic ammonium salt solution and the first passivation solution is 5 to 15 seconds; S32, the second inkjet print head prints the first passivation solution, and the interval time between the inkjet printing of the first passivation solution and the second passivation solution is 1 to 10 seconds; S33, the third inkjet print head prints the second passivation solution, and the interval time between the inkjet printing of the second passivation solution and the third passivation solution is 1 to 10 seconds; S34, the fourth inkjet print head prints the third passivation solution; The printing resolution range of the first inkjet print head is 100dpi~2400dpi, the printing nozzle droplet amount range is 1~50pL, and the injection frequency is 10~500kHz; the printing resolution range of the second inkjet print head, the third inkjet print head and the fourth inkjet print head is 100dpi~2400dpi, the printing nozzle droplet amount range is 1~50pL, and the injection frequency is 10~500kHz.

7. The method for parallel inkjet printing of perovskite thin films using a multi-ink path system according to claim 6, characterized in that: Gradient annealing is divided into three stages: The temperature in the preheating stage is 50-100°C, the heating rate is 2-5°C / s, and the duration is 2-5 minutes; The main annealing stage is 100-170°C, the heating rate is 1-2°C / s, and the duration is 10-30 minutes; The temperature is lowered to 50°C in the slow cooling stage, with a cooling rate of 0.5-1°C / s and a duration of 5-10 minutes.

8. A perovskite film, based on the method for parallel inkjet printing of a perovskite film using a multi-ink path system according to any one of claims 1 to 7, characterized in that: The perovskite film is prepared by a method of parallel inkjet printing of perovskite films using a multi-ink path system.

9. A perovskite solar cell based on the perovskite film according to claim 8, characterized in that: The perovskite solar cell comprises: transparent conductive glass, a hole transport layer, the perovskite film, an electron transport layer and a metal electrode which are arranged in sequence.

10. A method for preparing a perovskite tandem solar cell, based on the method for parallel inkjet printing of perovskite thin films using a multi-ink path system as claimed in claim 9, characterized in that: A hole transport layer, the perovskite film, an electron transport layer and a metal electrode are sequentially formed on the transparent conductive glass.

Images